Cam grinding apparatus



c. G. TREFETHE'N CAM GRINDING AIPARATUS Filed May 1e, 1930 3 sheets-.sheet l March 28, 1933.

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CAM GRINDING APPARATUS Filed May 16, 1930 3 Sheets-Sheet 2 xNvENToR M///V-S-S CHARL Es G. 7FEfETHEN www@ @1f-*5% NEY March 28, 1933. C. G. TREFETHEN 1,903,149

CAM GRINDING APPARATUS I iled lMay 16 1930 3 Sheets-Sheet 3 MTA/5555 NVENTOR Cf/A RL ES G. TREFE THEN Patented Mar. 28, 19133` UNITED STATES PATENT OFFICE CHARLES G. TREFETHEN, OF WORCESTER, MASSACHUSETTS, ASSIGNOR `'I O NORTON COM- Y PANY, 0F WORCESTER, MASSACHUSETTS', A CORPORATION OF MASSACHUSETTS CAM GRINDING APPARATS Application :tiled May 16, 1930. Serial No. l$52,932.

This invention relates to grinding machines and more particularly to a machine for grinding work having several spaced surfaces to be separately ground, such as a cam- 5 shaft, and the like.

In thev grinding of camshaftsor similar irregularly shaped objects where it is necessary to provide a rotary master form or cam to produce a relative movement between the wheel and the work and` thereby produce the desired contour on the work blank, it is necessary that suitable means be provided Vfor longitudinally moving the master cam or follower so as to position it in proper relation with the next master cam. In the ordinary cam grinding attachments, such as is in use in Aproduction grinding today, it is common practice to provide a master camshaft in which the master cams are closely spaced. This permits providing a rigid support for the master camshaft andrthereby eliminates the danger of vibration or flexing of the shaft during grinding and consequent inaccuracies in the contour and size of the product cam. It is also necessary that thev support for the master cam roller be. of substantial size and supported rigidly so that it will not vibrate and thereby aect the contour of the product cam. Vith the modern develop- 0 ments in the automotive field, it is necessary at the present time to grind camshafts having a large number of cam blanks formed integral with the shaft. For example in the new twin six and twin eight cylinder motors it is necessary to provide a camshaft having 24 or 32 cam blanks respectively. It `will readily be appreciated that with this number of product cams to be ground, it will be necessary to provide a corresponding numberof master cams on the master camshaft. It is impracticable to mount a long master camshaft such as is necessary for a shaft of this length with only two end bearings since there would not'be sufficient rigidity in the support for the master cam or the roller to properly transmit the desiredrelative movement between the product cam and the grinding wheel and insure proper grinding action to produce the predetermined contours onrthe blanks.

It is therefore'the primary object of this invention to provide a suitable construction so that very long camshafts having any number of cam blanks may be accurately ground to predetermined contours.

It is a further object of this inyention to arrange `the master cams in two sets spaced on opposite sides of an intermediate bearing and to provide a master cam roller for each set of master cams, so that both the master cams and the follower rollers may be rigidly supported against iexing or vibrating during the grinding operation. i

It is a stillV further object of this invention to provide a suitable mechanism whereby the follower rollers may be automatically indexed to successively engage each master cam in the two sets as the work table is traversed longitudinally to position the corresponding product cam in operative relation with the grinding wheel.

It is still another object of this invention to so construct the roller actuating mechanism that the master cam yroller engaging the first set of'mastercams may be indexed successively into operative relation with the master cams on the rst set, while the second roller remains stationary, and then when the first roller has moved from engagementwith the last .cam on the first set, the second roller will be brought into operative relation with the actuating mechanism so that Iit may be indexed successively into operative relation with the cams of the second set. Y

Heretofore in the cam grinding operations, as performedin production grinding, it has required considerable skill yand thought on the part of the operator to manually separate the master cam support from the grinding wheel, before he traverses the table to position the next cam in operative relation with the grinding wheel. VIf the operator neglects to properly separate the wheel and work before traversing the table, there is danger of the nose of thenext product cam being rammed into the side face of the grinding wheel, thereby spoiling the cam and possibly Vbreaking the grinding wheel. Likewise in a mechanism where the follower roller is indexed, automatically, as in the present construction, it is desirable that the work support be locked against longitudinal movement so as to prevent indexing of the master cam roller before the roller and master cam have been separated. If longitudinal movement of the roller were permitted before separation, the master cam roller would possibly be rammed into the side face of the next master cam thereby damaging the surface of the master cam roller and the master cam. This is very undesirable, since the accuracy of a cam grinding machine depends first on the rigidity of the mechanism, second upon the accuracy of the master cam and third upon the ability of the master cam and roller to maintain an accurate surface during a continuous production service of the machine.

It is therefore a further object of this invention to overcome such difficulties and to provide a suitable safety device which operates in conjunction with the rocking of the work supporting bar so that when the bar is in an operative position, longitudinal movement of the work table is prevented, and similarly to prevent rocking of the camshaft support to an operating position, before the master cam roller has been moved into operative relation with the next master cam and the next product cam positioned in operative relation with the grinding wheel.

Other objects of this invention will be apparent from the following disclosure. One embodiment of this invention has been illustrated in the drawings, in which like reference numerals indicate like parts:

Fig. 1 is a front elevation of a grinding machine embodying this invention;

Fig. 2 is a fragmentary perspective view on an enlarged scale showing the improved features;

Fig. 3 is a fragmentary end elevation showing parts broken away of the mechanism as illustrated in Fig. 2 5

Fig. t is a fragmentary longitudinal sectional view taken approximately on the line 4 4 of Fig. 3 showing the arrangement of the master cam roller operating mechanism;

Fig. 5 is a fragmentary elevation of the gear driving mechanism for the master cam roller, as shown in Fig. 2;

Fig. 6 is a fragmentary detail view taken approximately on the line 6-6 of Fig. 5; and

Fig. 7 is a fragmentary view of the parts shown in Fig. 6, taken approximately on the line 7-7 of Fig. 6.

A cam grinding machine, in accordance with this invention, is so arranged that the grinding wheel and cam blanks may be moved relatively towards and from each other to grind the desired contour on the blank by means of two sets of master cams and followers suitably connected for this purpose. This invention contemplates an apparatus in which a relative traversing of the grinding wheel and work automatically indexes the master cam rollers to position one of them in front of the proper master cam. The preferable construction is one in which the relative traversing movement between the grinding wheel and the work blank indexes one master cam roller to position it in operative relation with successive master cams on one set, while the second master cam roller is stationary. When the first master cam roller moves away from the last master cam on the first set, it operates to move the second master cam follower so that it is in driving relation with the control mechanism and is arranged to be moved successively into engagement with the cams of the second set, while the first master cam roller remains stationary. rlhis feature of the invention is an improvement over the co-pending application of T refcthcn and Belden, Patent No. 1,783,755 filed June 29, 1927.

To accomplish a further object of the invention, a safety device is provided which preferably comprises a locking arm connected to the rocking bar which is arranged to prevent longitudinal movement of the work table while the cam shaft is in operative engagement with the grinding wheel. This also serves to prevent rocking the work and the master cam to operative positions before the product cam is in proper position relative to the grinding wheel and the master cam roller is in its correct location opposite the proper master cam.

1n the form illustrated, this apparatus comprises an attachment adapted to be applied to any well known cylindrical grinding machine in which a grinding wheel is mounted on a wheel slide and is adapted for transverse movement of the base. rEhe work supporting table is arranged to slide longitudinally relative to the operative face of the wheel. The cam attachment is mounted upon the work table and carries the master camshaft in axial alignment with the camshaft to be ground. In the improved construction, a feeding mechanism is provided for moving the grinding wheel towards and from the work and is connected to a fluid pressure mechanism which operates to rock the master cam from contact with the master cam follower into an inoperative position.

As illustrated in the drawings, the grinding machine has a base 11 carrying a wheel slide 12 on which a grinding wheel 13 is rotatably supported. A table 15 is mounted on the front portion of the base and is adapted for a traversing movement longitudinally of the machine base by means of a hand wheel 16, fixed on the outer end of a shaft 17. The inner end of the shaft 17 carries a pinion 21 meshing with gearing 28 which in turn meshes with a rack 22 so that rotation of the hand wheel 16 is transmitted through patent to Norton No. 762,838 of June 14,

In order that lwork of irregular cross section may be ground, any suitable mechanism may be utilized whereby the work axis and the grinding wheel axis may be moved relatively towards and from each other during the grinding operation, so as to generate the desired contour on the work piece. In the preferred construction, the work supporting mechanism is so mounted that it may rock towards and from the operative face of Ythe grinding wheel to produce the desired contour upon the camshaft to be ground. As shown in the drawings, the supporting brackets 25 and 26 are mounted on opposite ends of the table 15. The rock bar 28 has a pair of trunnions 29 and 30 projecting from its opposite ends. The trunnions 29 and 30 are supported for rotation in the brackets 25 and 26 respectively. The headstock member 32 and the footstock 33 are mounted on the upper surface of the rock bar 28. These members are provided with work supporting centers 34 and 35 to support the work piece or camshaft 40 during the grinding operation. The headstock 32 carries a driving member 37 adapted to engage a driving dog 38 which is clamped to one end of the camshaft 40.

To transmit a rocking motion to the camshaft 4() so as to cause a movement towards and from the grinding wheel and produce the desired predetermined contour on the work blank, a master cam is mounted to rotate with the work and a' cam follower is mounted on the. table and arranged for en* gagement with the master cam. In the grinding of long shafts, such as are used in some of the modern multi-cylinder automobiles, it is necessary to have a master camshaft of considerable length even though the master cams are closely spaced on the shaft. In order that the shaft may be supported against vibratory movement which would detrimentally affect the grinding operation, the master camshaft is preferably made of a heavy construction and is supported for rotation in bearings 42 and 43 at each end of the shaft and an intermediate bearing 45 located centrally of the shaft. This permits the shaft to be rigidly supported so that the contour of the product cam may be accurately controlled. A plurality of master cams are mounted upon a shaft 41, and these are preferably arranged in two sets, a set of master cams 46 located on one side ofthe intermediate bearing 45, and a set of master cams 47 located on the opposite side of the intermediate bearing. Similarly, it is desirable that the master cam rollers, which are rotatably supported on the table 15, be held rigidly so as to prevent any vibration and a consequent inaccuracy in the surface or contour of the cam blank. To provide a rigid mounting of the master cam rollers, it is preferable to provide a shaft 50 for the rollers which is supported in bearings 51 and 52 located adjacent to the ends of the shaft. To `prevent vibration or flexing of this shaft during the grinding operation, an intermediate bearing support 53 is provided. Two master vcam rollers are mounted one on each side of the intermediate bearing 53, one roller 54 which is arranged to be successively indexed into operative relation with the master cam 46, and a secondroller 55 which is supported on the other end of shaft 50 which is arranged to be successively indexed into operative relation with the other set of master cams 47. It will be readily appreciated from this construction, that by providing an intermediate bearing support for both the master camshaft 41 and the master roller shaft 50, a rigid support is obtained which will prevent flexing of either of said shafts, and thereby provide a construction in which the master cams will operate to accurately control the rocking movement of the supporting bar 28 and the contour of the product cam on the shaft 40.

It is desirable that one of the rollers 54 or 55 be indexed into successive engagement with the master cams on its co-acting set, while the other roller remains inoperative. It is also desirable that the rollers be indexed in timed relation with the table movement so that when the operator traverses the'work table longitudinally to bring a product cam into operative relation with the Vgrinding wheel, the master cam rollers automatically index so that they will be in proper relation with the master cam corresponding to the product cam being ground. In the preferred construction, this may be accomplished by means of a dog bar 60` which is fixed at one end to a bracket 61 supported on the base 11. The other end of the bar is supported bythe guides 62 and 63 which are carried by the webs 64 and 65 supported on the table 15. The bar 60 is provided with a plurality of adjustable dogs 66 of a number corresponding to the cams on the camshaft to be ground.

A suitable gear mechanism is connected to index the master cam rollers so that when the table 15 is moved longitudinally,'the dogs on the bar will automatically index the master cam rollers in proper relation with the cams to be ground., This mechanism preferably comprises a star wheel 67 which is Vsupported on the outer end of a stud 68.

The star wheel 67 is arranged Vin the vpath of movement of the dogs 66. The stud 68 also supports a gear 69 meshing with an intermediate gear 70 mounted on a stud 71 supported by a bracket 72. The gear 70 meshes with a gear 7 3 on the stud 74 which is supported by a bracket on the web 65. rIhis stud 7 3 also carries pinions 76 and 77 which mesh with the rack bars 78 and 79 respectively. The rack bars 78 and 79 are supported and freely slidable within grooves in a guide block 80 which is fixed rigidly to the webs 64 and 65. The rack bars 78 and 79 are connected by brackets 81 and 82, respectively, to the master cam rollers 55 and 54, respectively. The bracket members 81 and 82 are preferably formed as yoked members engaging opposite sides of the rollers 54 and 55 so that when the rack bars are moved longitudinally relative to the machine base, the bracket members 81 and 82 will slide the rollers 55 and 54 longitudinally to position them in operative relation with the proper master cam. It will be readily appreciated from the foregoing description that the longitudinal movement of the table operates to move the star wheel 67 relative to the dog bar 60, and when the dog 66 on the bar contacts with the star wheel, it turns the star wheel and the train of gears to transmit an endwise movement to the rack bar 78 or 79 to cause an endwise positioning movement to the roller 55 or 54.

1t is desirable that one of the rollers remain stationary while the other roller is being indexed so that the roller 55, as shown in Fig. 2, will be indexed into successive operative relation'with the set of master cams 47. while the roller 54 remains inoperative. This is accomplished by providing rack bar 79 having teeth adjacent to the right-hand end (Fig. 2) so that the rack teeth are not in engagement with the pinion 77. The roller 55 is indexed successively into engagement with the cams 47, while the roller 54 remains stationary. ri'fhe rack bar 78 is provided with a projecting end 84 which is arranged to engage the bracket 82 when the roller 55 is indexed from the last cam 47 and thereby moves the rack bar 79 to bring the rack teeth into engagement with the pinion 77. At the same time the rack teeth on the rack bar 79 are brought into engagement with the pinion 77, the rack bar 78 has moved a suiicient distance toward the left (Fig. 2) so that the teeth of the rack bar 78 run out of mesh with the pinion 76. Continued traversing movement of the work table towards tl e right, as viewed in Fig. 2, will index the roller 54 successively into operative engagement with the master cams 46. The parts of this indexing mechanism are so arranged that the grinding operation on one cam shaft may start grinding at the headstock end of the shaft and grind successive cams toward the footstock and on the next camshaft start grinding at the footstock end and bring the cams successively into operative relation with the grinding Wheel by moving the table in the opposite direction.

To prevent overrunning of the gear mechanism due to the indexing movement of the dogs, a suit-able friction device is provided, as illustrated in Figs. 7 and 8. This device may comprise a member 88 which partially surrounds the stud 68 and is provided with a (zo-acting part 89 to completely surround the stud 68. These parts are held in frictional engagement with the periphery of the stud 68 by springs 90 and 91 which in turn are supported by the studs 92 and 93. The tension of the springs is adjustable by the nuts 94 and 95 respectively so that the friction between the members 88, 89 and the stud 68 may be varied as desired. The member 88 is held against rotary movement by a stud 96 which is fixed on a bracket 97 which also supports the stud 68. rEhe operator may, by varying the tension of the springs and 91, obtain the desired friction to prevent an excessive movement of the indexing parts as the table is traversed, thereby preventing overindexing of the master cams due to the movement of the star wheel.

Any suitable driving mechanism may be utilized to rotate the master camshaft and the camshaft to be ground. In the preferred construction, a simplified drive is illustrated which comprises a pulley 100 mounted on the outer end of the shaft 101 which is supported by a bearing 102. The pulley is rotated by a belt 103 from any suitable source of power. The shaft 101 is connected by a flexible universal joint 104 to a shaft 105 which is connected by a flexible universal joint 106 to the master camshaft 41. It will be readily apparent that rotation of the pulley 100 will be transmitted through the shaft 101 and the shaft 105 to rotate the master camshaft and also the product camshaft. rlhe bracket 102 is fixed to the table 15 and the pair of universal joints provided to permit the rocking movement of the camshaft support during the grinding operation.

A mechanism is provided to yieldably maintain the master cams 46 and 47 in contact with the periphery of the master cam rollers 54 and 55. As shown in the drawings, the rock bar 28 is provided with a projecting arm 110. The lower end of a rod 111, is connected by means of a pin 112 to the outer end of the arm 110, and is slidably supported within a cylinder 113. The cylinder is provided with projecting trunnions 114 which are supported in brackets 115 and 116. These brackets are fixed to the plate 117 which is formed integrally with the webs 64 and 65. The trunnion mounting for the cylinder permits a rocking movement of the cylinder as the rock bar is oscillated during the grinding operation. The upper end of the rod movement toward the work is preferably spring 121. The lower end of the spring is.

, supported by a collar 122 which is slidaby mounted on the rod 111 and is fixedly mounted relative to the cylinder 113. .The tension of the spring 121 is sufficient to maintain the master cams 46 and 47 in contact with the periphery of the master cam rollers 54 and 55 during the grinding operation. In order thatthe master cams 46 and 47, as well as the product camshaft 40, may be withdrawn for engagement with the follower rollers 54 and 55 and the grinding wheel13 respectively, to permit the shaft 4() to be indexed to move the next cam into operative relation with the grinding wheel and also to permit the follower roller 54 or 55 to Vbe indexed into alignment with the next master cam, a mechanism is utilized to rock the bar 2'8 against the tension of the spring 121. In the preferred construction, a device operated by air pressure is provided having a cylinder chamber 125 in the upper end of the cylinder 113 carrying a piston 126 slidably mounted therein. The piston-may be direct- 'ly connected to. the rod 111 so that it `will slide within the cylinder yas the rod moves relative thereto. In the preferred construction, however, as shown in Fig. 3, the piston 126 is constructed as a separate' member which is adapted to contact with thev upper faceV of the colla-r 118. As fluid under pressure is admitted through the port 127 in the cylinder head 128, the piston is forced downwardly against the tension of the spring 121, to rock the bar 28 andV withdraw the master cams 46 and 47 and the camshaft 40 from contact with the master camrollers 54 and 55 and the grinding-wheel 13 respectively. After the table 15 is traversed to bring the next product cam on the camshaft 40 into alignment with the grinding wheel 13,V the fluid pressure within the chamber 125 is reduced and the released tension of the spring 121 moves the rod 111 upwardly to roel?` the bar 28 and the master cam 46 or 47 into operative engagementwith the master cam roller 54 or 55 and the grinding wheel 13.

The wheel slide 12 may be fed towards and lfrom the work support by any suitable means, such as a half-nut 130 depending from the under side of the slide and adapted to'engage a feed screw 131 mounted in suitable bearngs (not shown) in the'base of the machine. A hand wheel `132 ismounted on a shaft 133 to turnrthey feed screw 131 to produce a feeding action of the grinding wheel. By rotating the hand wheel 132, the feed screw 131 may be turned in either direction to feed the grinding wheel toward or from the work as desired. The

limited by means of a stop lever 134 adapted to contact with an abutment 135 on the hand wheel 132. n

To operate the cylinder mechanism so as to automatically withdraw the cam in proper time, a valve is provided which is operated in tim-ed relation Vwith the moving parts of the grinding machine. The valve mechanism is operated preferably in timed relation with the wheel feeding mechanism to rock the bar 28 when the operator starts to feed the wheel either toward or away from the work. As shown in the drawings, a valve mechanism comprises a casing 140 fixed within the base 11. A valve piston 141 is slidably mounted within the casing 140. The extended portion of the piston 141 is provided with a rack bar 142 meshing with a gear 143 on a shaft 144. In operation of the mechanism, it is desirable that the mechanism be so constructed and arranged that continued movement of the feed mechanism to position the wheel is permissible after the valve has been shifted. To accomplish this, a friction disk 145 is provided which vpermits a rotary movementY of the wheel feed without moving the valve 141. This friction mechanism is not considered part of the present invention and for further description reference may be had to the Patent No. 1,783,755.

During the grinding operation, the valve piston 141 is in the position shown in Fig. 1,'that is, with the valve port closed. The port 146 in the valve is connected by a pipe 147 with the port 127 within the cylinder head 128. When the feed wheel 132 rotates to feed the wheel rearwardly, the gear 143 meshing with a gear 150 on the feed screw moves the rack bar 142 and valve piston 141 toward the leftvas viewed in Fig. 1 into the position illustrated in broken lines. This movement opens a port 151 and permits fluid under pressure to pass througha pipe 152, from any suitable source, into the pipe 147 into the cylinder chamber 125 so as to rock the bar and remove the master cams and the product Acamshaft from engagement with the master cam rollers and the grinding wheel respectively. On the forward feeding movement of the grinding wheel rotation of the feed screw operates through the gear 150 and gear 143 to move the rack bar 142 and piston 141 toward the right into a position such as is illustrated in full lines in Fig. 1. This permits air or fluid under pressure t`o pass outwardly from the cylinder chamber through the pipe 147 and to exhaust through a port 154thereby permitting the Vrocking bar to rock under the tension of the spring 121 and move the master cams and the product camshaft into operative engagement with the master cam roller and the grinding wheel respectively. y

To attain one of the objects of this invention, namely to prevent longitudinal movement of the work table during the grinding ope-ration, it is desirable to provide suitable mechanism operating in timed relation with the oscillating movement of the rock bar so that it is impossible to traverse the work when it is in an operative position relative to the grinding wheel. This feature prevents damage to the camshaft and also prevents ramming of the master cam rollers into the side faces of the master cams, thereby injuring the surface of the master cam roller and also the master cam which would in turn detrimentally aHect the contour of the cam produced from the given master cam. In the preferred construction, the rock bar 28 is provided with a projecting arm 160 having a spring pressed plunger 161 extending downwardly from its outer end. The plunger 161 is adapted to engage any one of a plurality of notches 162 in a bar 163 which is supported on the table 15 by brackets 164 and 165. The notches in the bar 163 are spaced to correspond with the spacing of the product cams on the shaft 40 so that when a product cam is brought into operative position relative to the grinding wheel 13, the plunger 161 will drop into or engage the notch 162 corresponding to the product cam. It will be readily appreciated that when the plunger 161 engages any of the notches 162 in the bar 163 further endwise movement of the table will be prevented until the rocking bar has been rocked to an inoperative position, thereby removing the master cams and the product cam away from the master cam roller and the grinding wheel respectively. The plunger 161 is preferably spring pressed and is provided with a suicient amount of endwise movement so that the plunger 161 may be maintained in operative engagement with the slots 162 during the normal oscillating movement of the rock bar while the cams are being ground. To withdraw the pin 161 from the notches 162, it is necessary that the bar be rocked by the fluid pressure mechanism to an inoperative position.

Vhen the bar 28 rocks to an operative position, the plunger 161 contacts with the fiat upper surface of the bar 163 and the upper surface of the plunger 161 will bottom within its aperture and prevent the master cam from contacting with the roller and the product cam from contacting with the grinding wheel, until the table has traversed a suflicient distance to bring pin 161 into engagement with a slot 162.

The operation of the mechanism will be readily apparent from the foregoing disclosure. The camshaft 40 is rotatably mounted on the centers between the headstock and footstock and is driven by a driving member 37. Assuming the table to be moved in an extreme position toward the right, as viewed in Fig. 1, or left, as viewed in Fig. 2, the

` operator then turns the feed wheel 132 in a eountercloekwise direction to feed the grinding wheel 13 toward the work. This movement slides the valve piston toward the right into the position illustrated in full lines in Fig. 1 and permits the air to exhaust from the cylinder chamber 125 thereby permitting the rock bar 28 to rock the master cams and the shaft 40 into operative relation with the rollers 54 and 55 and the grinding wheel 13 respectively. The spring 121 maintains the master cams and roller in proper contact during the grinding operation. The first cam is ground and then the feed wheel is turned in a clockwise direction to remove the wheel from operative position and this movement operates through the gear train to move the valve piston 141 toward the left, as viewed in Fig. 1, to admit air under pressure to the cylinder chamber 125 and thereby rock the bar 28 and remove the master cams and the product shaft from operative engagement with the rollers and grinding wheel respectively. rThe traverse wheel 16 is rotated to slide the work table longitudinally toward the left, as viewed in Fig. 1, or toward the right, as viewed in Fig. 2, to position the next product cam in operative relation with the grinding wheel. This movement automatically indexes the master cam roller 55 into the position as illustrated in full lines in Fig. 2 into engagement with the next master cam of the set. This cycle of operation is then continued until the master cam roller is indexed from engagement with the last master cam 47. During this last indexing movement the projection 84 of the rack bar 7 8 engages the bracket 82 and brings the rack 79 into mesh with the pinion 77 and the master cam roller 54 is then indexed as the table is traversed into successive engagement with the master cams 46. This operation continues until the entire number of cams on the shaft have been ground. When the next camshaft has been inserted in operative position on the machine the grinding operation is started from the footstoek end of the support and the table is moved longitudinally toward the right, as viewed in Fig. 1, or toward the left, as viewed in Fig. 2, to bring successive cams into operative relation with the grinding wheel. It will be readily appreciated from the foregoing description that the master cam rollers 54 and 55 will index as the table is moved in either direction.

Having thus described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. A cam grinding machine comprising a grinding wheel and a support for a set of cam blanks movable relative thereto, master cams and cam followers which are relatively movable, means associated therewith for moving the cam blanks and wheel relatively in accordance with the relative movement between a master cam and its follower to llO grind a desired cam contour, said master cams being arranged as two sets, each set having a follower co-acting therewith, and mechanism for automatically indexing one of the followers longitudinally relative to its set of cams while the other remains inoperative and thereafter indexing the second follower while the first remains inoperative.

2. A cam grinding machine of the type covered by claim l having a longitudinally movable table supporting the cam blanks and master cams and means actuated by movement of the table for indexing the master cam followers successively.

3. A grinding machine of the type covered by claim l having a longitudinally movable table carrying said cams and cam blanks, two rack bars slidably mounted on said table and connected to move the cam followers independently, stationary indexing members on the machine and means operated by contact with indeXing members as the table is moved for moving first one and then the other of said rack bars.

t. A cam grinding apparatus comprising a base, a grinding wheel and a movable table thereon, a support for a set of cam blanks on the table which is movable toward and from the wheel, a plurality of master cams arranged in two sets on the support, means including two master cam followers co-acting with the sets of master cams to move the cam blanks, two rack bars connected to index-the followers independently into successive engagement with the master cams, dogs on the base, and a gea-r drive comprising two gears arranged to mesh with said rack bars which are rotated by the dogs when the table is moved, said parts being so arranged that one rack bar is moved by its gear to index the corresponding follower into successive engagement with the cams of the first set and thereafter the second rack bar is indexed to move its follower successively into engagement with the second set of master cams.

5. A cam grinding machine having a rotatable grinding wheel movable transversely of the base, a camshaft support arranged to move a camshaft longitudinally to bring successive cam blanksY into operative relation with the grinding wheel, said support being arranged for lateral movement towards and from the grinding wheel, means including a set of master cams and a follower to move the cam blanks and produce a predetermined contour thereon, means operat- 1 ed by moving the support laterally for locking the cam blank support against longitudinal movement and with a cam blank in any one of several operative positions relative to the wheel, and means for releasing the locking means when the cam blank is moved away from the wheel.

6. A cam grinding machine having a base,

a rotatable grinding wheel movable transversely thereof, a tableV movable longitudinally on said base, a pivotally mounted work support arranged to rotatably support a camshafthavinga plurality ofsp aced cam blanks, means including a set of master cams and a follower arranged to rock said support towards and from the grinding wheel as thev camshaft rotates to grind a desired contour on the cam blank, means to traverse the table longitudinally to successively present cam blanks to the grinding wheel, means to rock said support to and from an operating position before and after grinding, a notched bar iiXedly mounted on the base, and a pin 2.

on said support arranged to engage said notches to prevent longitudinal traversing of the table until said support has been rocked to an inoperative position.

7. A cam grinding machine having a base, a rotatable grinding wheel and a work support which are relatively movable longitudinally and laterally for grinding a series of cam blanks, means including a set of master cams and a follower arranged to cause said l lateral movement and determine the contour of the cam blanks, means to cause the relative longitudinal movement of the wheel and work to successively present cam blanks to .the wheel, means to cause relative lateral movement between the wheel and cam blanks to separate them or bring them into grinding contact, and means to prevent a relative lateral movement towards an operative position until a cam blank has been positioned longitudinally in an operative relation with the grinding wheel.

8. A cam grinding machine having a base, a rotatable grinding wheel movable transversely thereon, a table movable longitudinally on said base, a pivotally mounted work support arranged to rotatably support a camshaft, means including a set of master cams and a follower arranged to rock said support towards and from the grinding wheel as the camshaft rotates to grind a desired contour on the cam blank, means to traverse the table longitudinally to successively present cam blanks to the wheel, means to rock said support to and from an operating position before and after grinding, and means to prevent rocking said support and camshaft to an operative position until a cam blank has been positioned in an operative relation with the grinding wheel.

9. A cam grinding machine comprising a grinding wheel and a support for a set of cam blanks movable relative thereto, a master camshaft, a plurality of master cams lon said shaft, bearings on said support to support the ends of said shaft, an intermediate bearing on said support for supporting the center of said shaft and dividing said master cams into two sets, a master cam follower for each of said sets, means associated therewith i for moving Jche cam blanks and Wheel relatively in accordance with the relative mcvement between a master cam and its follower to grind a desired cam contour, and an indexing mechanism for automatically indeX- ing one of the followers longitudinally relative to its set of earns While the other remains inoperative and thereafter' indexing the second follower While the first remains inoperative.

Signed at Vorcester, Massachusetts, this 14th day of May, 1930.

CHARLES G. TREFETHEN. 

